Toothed power transmission belts are finding increasing usage in applications, such as office printing devices, including printers and facsimile reproducers.
With the toothed drive belts of the prior art, problems arise at times in the failure of the mechanism to maintain the printed lines straight. It has been found that such improper prints results from belt deflection in engaging with and disengaging from the drive pulleys.
One attempted solution to this vexatious problem has been to provide increased tension in the belt. Another attempted solution is to arrange the belt and pulley so as to have substantially no backlash. These attempted solutions, however, are not fully satisfactory, as they adversely affect the durability and life of the belt as well as raising problems in dumping of the teeth from the pulley, particularly where the backlash is attempted to be eliminated.
The provision of toothed belts in power transmission provides for synchronized driving between elements of the mechanism. Such synchronized driving is highly desirable in the robot industry wherein accurate correlation between the disposition of different parts of the mechanism must be maintained.
In order to provide more smooth engagement and disengagement between the belt and the pulley teeth, it has been considered desirable to provide backlash therebetween. On the other hand, such backlash permits deflection of the teeth of the belt during such engagement and disengagement relative to the pulley, tending to wear the teeth and tend to separate the teeth from the belt body after a relatively short period of use.